Rotary kilns and dryers or other like apparatus



Feb. 6, 1962 3,019,835

ROTARY KILNS AND DRYERS OR OTHER LIKE APPARATUS R. L. F. MAURAND 5Sheets-Sheet 1 Filed July 8. 1957 Feb. 6, 1962 R. F. MAURAND 3,019,835

ROTARY KILNS AND DRYERS OR OTHER LIKE APPARATUS 5 Sheets-Sheet 2 FiledJuly 8, 1957 Feb. 6, 1962 R. F. MAURAND 3,019,835

ROTARY KILNS AND DRYERS OR OTHER LIKE APPARATUS 5 Sheets-Sheet 3 FiledJuly 8, 1957 ROTARY KILNS AND DRYERS OR OTHER LIKE APPARATUS Filed July8, 1957 Feb. 6, 1962 R. F. MAURAND 5 Sheets-Sheet 4 5- MwMTMT Feb. 6,1962 R. F. MAURAND 3,019,835

ROTARY KILNS AND DRYERS OR OTHER LIKE APPARATUS Filed July 8, 1957 5Sheets-Sheet 5 ZY WBMMAM nited States France Filed July 8, 1957, Ser.No. 679,472 Claims priority, application France July 15, 1956 11 Claims.(Cl. 159-9) In industry, it is frequently necessary to dry more or lessfluid pulp Or slurry in order to obtain the material or materials whichthey contain, in a solid form. When rotary kilns or dryers are used forthis purpose, comprising a long rotating cylinder, slightly inclined tothe horizontal, through which pass hot gases circulating in counter-flowwith a flow of liquid slurry introduced at the higher extremity or inputside of the cylinder, some difficulties are encountered reducing theproduction of the apparatus mainly as a result of the overflowing of theslurry on the upstream side of the cylinder, and of the necessity ofensuring a suflicient outlet passage for the gases.

In these rotary kilns, in order to maintain a suflicient quantity offluid slurry to be treated, it is known to provide a retaining ring orcollar at the upstream side of the cylinder, the radial height of thecollar controlling the overflow level of the slurry. A collar of thiskind enables only a relatively small height of slurry to be maintainedin the rotating cylinder of the drying apparatus, since it reducessimultaneously at the outlet the section of passage for the hot gasesrequired for drying and in some cases for burning the pulp or slurry.

This invention overcomes the drawbacks referred to above and enables ahigh level of fiuid slurry to be maintained in the rotating cylinder,slightly inclined to the horizontal, of a kiln or dryer, withoutsimultaneously further reducing, at its upper extremity with respect tothe common structures, the section of the cylinder available for thepassage of the hot gases, by reason of the elimination or substantialreduction of the usual collar.

According to the invention, a rotary inclined kiln intended for treatinga fluid slurry, and especially for drying the same, comprises incombination with a rotating cylinder slightly inclined to thehorizontal, a dam-forming member such as a trough or a plate, extendingover a part only of the radial height of the cylinder, mounted at theupper extremity of the kiln in such manner as to be maintained againstrotation but to allow relative movements of the cylinder in the axialand circumferential directions, and a fluid-tight joint interposedbetween the said damforming member and the cylinder, the said jointbeing so arranged as to permit the said displacements.

The fluid-tight joint may be formed by wearing parts, metallic orotherwise, secured respectively to the rotating cylinder and to thedam-forming member, and pressed one against the other in any appropriatemanner. Alternatively, it may be formed by fluid-tight segments slidingon the dam-forming member or on the cylinder, and mounted between ringsrigidly fixed to the cylinder or to the dam-forming member respectively.

The following description made with reference to the accompanyingdrawings (which are given by way of example only and not in any sense byway of limitation) will make it quite clear how the invention may becarried into effect.

FIGURE 1 is a diagram. showing the known arrangement of a retainingcollar for the pulp at the upper part of a rotary cement kiln.

FIGURE 2 is a diagrammatic longitudinal cross-section I Patented Feb. 6,1962 ice of the upper part of a rotary kiln or dryer equipped with theretaining device according to the present invention.

FIGURE 3 is an end view corresponding to FIGURE 2, looking from theright-hand side of this figure, the stationary hood being removed.

FIGURE 4 is a view in perspective of the upper extremity of a kilnequipped with the device shown in FIG- URE 2.

FIGURE 5 is a view in elevation of an alternative form of constructionof the device for preventing overflow of the slurry.

FIGURE 6 is a vertical cross-section passing through the line VI-VI ofFIGURE 5.

FIGURE 7 is a vertical diagrammatic cross-section of a mechanism whichcan be used with the devices of FIGURES 4 and 5 to apply the dam-formingmember against the extremity of the rotating cylinder.

FIGURE 8 is a view in perspective with cross-section and parts brokenaway, of a method of carrying the invention into effect which provides alarge outlet section.

FIGURE 9 is a perspective view of a form of embodiment in which thefluid-tightness at the upper part of the kiln is obtained by fluid-tightsegments.

FIGURE 10 is a diametral cross-section of an alternative form ofconstruction of the device shown in FIGURE 9. FIGURE 11 is a partialcross-section on a larger scale of the fluid-tight seal used in thedevices of FIG- URES 9 and 10.

FIGURE 12 is a view in perspective with cross-section I and parts brokenaway, of an alternative form of construction of the device shown inFIGURE 9.

The invention will be explained hereinunder in its application to rotarykilns used for the manufacture of cement, in which it can be employedwith advantage, but it will be clearly understood that the device can beapplied to all kilns and dryers comprising a rotating cylinder slightlyinclined to the horizontal, in which a relatively fluid slurry isintroduced at the upper extremity.

The slurry. employed for the manufacture of cement is a viscousliquidformed of a mixture of water, limestone and clayelements,.intimately mixed. This slurry is introduced at the upperextremity of a rotary kiln heated by a burner axially disposed at thelower extremity. The slurry is first of all dried in the upper part ofthe kiln by the combustion gases, the solid elements obtained being thenbrought up to a sufflciently high temperature, in a lower portion, tocause the formation of clinker which is extracted from the lower part ofthe kiln.

During its drying, the slurry becomes more and more viscous and, for acertain content of water, it can no longer spread out like a liquid atan appreciable speed, but it is still not sufliciently dry to form abank of pulverulent material moving downwards on account of the kilnrotation. In this semi-solid state, the downward flow of the slurry isonly eitected at a very low speed under the mechanical action ofinternal members (chains or the like). An accumulation of material thusresults in the corresponding zone of the kiln, producing a chokingeffect and the formation of a pool of liquid slurry on the upstream sideof this obstruction.

In order to maintain in the kiln a suflicient quantity of slurry and toavoid overflowing on the upstream side, there is usually fixed on theextreme upper edge of the shell 1 (see FIG. 1) forming the outer metalcasing of the kiln, a ring 01 collar of sheet steel 2, the centralopening '3 of which is intended to provide a passage for the hot gasesflowing through the kiln and passing into the stack. The maximum heightwhich the pool of slurry 4 can reach at the upper part of the kiln, isthus determined by the internal diameter of the collar 2.

When it is desired to increase the output of a kiln, the tendency is toincrease the height h of the collar so as to increase the quantity ofslurry retained, but in so doing the section of the outlet orifice 3 forthe gases is simultaneously reduced, whilst the volume of these gasesincreases with the output. In order to overcome this difscurry, theinvention provides for the elimination of the collar or to reduce itsheight to a smallvalue and to provide a fixed dam member suitably placedwith respect to the upper extremity of the kiln, in order to retain theslurry in the bottom portion of its section, but leaving for the passageof the gases all the upper portion of the circular ringwhich would beclosed if the usual type of collar was employed. By this arrangement,the section of passage available for the gases may attain three timesthat whichwould be left by a standard type of collar which has theheight of the circular segment. With the device in accordance with thiinvention, there may thus be provided a dam part or member whichmaintains a pool of slurry of considerable height whilst preservingacceptable possibilities of draught.

FIGS. 2 and 3 show in diagrammatic form the device according to theinvention. In these figures, the upper cylindrical extremity of the kiln1 rotates in a stationary hood 6, which is connected to the stack by aconduit 7, with the interposition of a known fluid-tight joint 5avoiding that fumes may escape out of the hood while permittinglongitudinal and radial expansion of the kiln. Said joint 5 may be, forinstance, of the type comprising an asbestos packing-gasket 5 locatedbetween a pair of annular metallic discs 5' secured on the sheet-metalof hood 6 around the opening provided therein for the passage of saidkiln, said gasket being in rubbing contact with the outer surface of theshell of kiln 1. The usual collar 2 is reduced in radial dimension tothe value just necessary to enablean annular wearing sliding member 8 tobe fixed to it; In the hood 6 is suspended a dam plate 9, the upperhorizontal edge of which is at a level a little above the level 4 to bemaintained torthe pool of slurry. 'On the face of this plate 9 which isdirected towards the kiln is fixed a further wearing sliding memher Notsuflicient size to overlap the circular segment which represents incross-section the pool of slurry, and so as to bear against the wearingsliding member 8 over the entire circular part of this segment. Oneither side of the dam-plate 9, and along a line crossing the afore-.mentioned segment, is fixed a pair of cables 11 passing through the hood6 which pass around a pair of pulleys 13 and carry weights 14. Thepulleys 13 are so located as to maintain the strands of the cables whichare secured to the plate 9, substantially parallel to the axis of thekiln. Thus, the wearing members 8 and are kept applied against eachother by the action of the weights 14 which, through the cables 11,apply on said dam-plate forces acting in a direction substantiallyparallel to the rotary kiln, so that said members form one with anothera fluid-tight rotary seal (which may be lubricated, if required), sothat it is possible to maintain in the kiln a h ight of slurry equal tothe rise f of the circular segment defined by the upper straight edge ofthe wearing member 10. By virtue of the weights 14, the wearing membersare keptin contact in any position of the kiln on the supportingrollersand whatever may be the amount of its variation in length due tothe expansion of the shell during working.

FIG. 4 shows a form of practical embodiment of the invention showndiagrammatically in FIGS. 2 and 3. In

FIG. 4, the annual wearing sliding member 8 is fixed,

for reasons of construction, on a further ring 8a which is secured byany suitable means to the collar 2 of the kiln. The non-rotating wearingsliding member of the fluid tight seal (not shown in FIG. 4) is similarto the member. 10 of FIG. 2, and forms a rectangular plate, the lowercorners of which are removed, said plate being secured by anyappropriate means against a supporting dam plate 9. The plate 9 isitself welded or otherwise secured to a bar 15 pivoted at its twoextremities to a pair of suspension rods 16 in turn pivoted to a pair ofimmovable brackets (not shown) secured, for instance,

to the wall of the stationary hood. At each extremity of the supportingbar 15 is provided a stirrup 17 to which may be connected the cable 11of FIG. 2.

The relative movement between the darn member 9 and the rotatingfluid-tight member 8 may be permitted by other means than the pivotalsuspension of the member 9. i

In FIGS. 5 and 6 there has been shown a form of embodiment comprising asliding guide. The fluid-tight wearing member 8, similar to that shownin FIG. 4, is secured as in the previous case to a ring 8a which is inturn secured to the collar'2 of the kiln- The dam plate 9, to which isattached the fixed wearing member 10 is carried by a bar 15 to which aresecured two stirrups 17. At each extremity of the bar 15 is provided acarrying and guiding shoe 18, which in the case of the exampledescribed, is of U-section. The two shoes each slide in a slide-trackparallel to the axis of the kiln, formed by two angle irons 19 suitablysupported on the lateral wall of the stationary hood 6. The applicationof the fixed wearing sliding member 10 against the rotating ring 8 andconsequently the fluid-tight seal of the lower segment of the kilnlimited to the upper edge 9 a of the plate 9, is obtained by the actionof two weights 14 (see FIG. 7) acting respectively at both extremitiesof the bar 15 on the stirrups 17, to which are connected the suspensioncables 11' for the weights, the cables passing round the pulleys 13. Apacking gland 12 is provided for the passage of each cable 1 1 throughthewall of the hood 6 in order to avoid intakes of 'air which wouldadversely affect the draught. i

In the example of construction shown in FIG. 8, the section of passageavailable to the gases at the upper part of the kiln is increased to themaximum extent. The shell 1 of the kiln again enters the hood 6 for acertain distance, the fluid-tightness at its entry being eifected bymeans of the usual seal 5. The usual collar2 (see FIG. I) retained witha reduced height in the previous embodiment, is in this casecompletely'elirninated and is replaced by a ring 20 formed in the caseof the example described, by a bent angle'iron mounted on the outwardside of the shell 1, so as to form an external radial flange 291:.

secured by any suitable means. An external ring 21,

having an internal diameter equal to that of the shell 1,

which is aligned with the inner surface of the shell 1, at

a height equal to the, maximum height h provided for the lake of slurryin the, kiln. The assembly formed by the ring 21, the wearing slidingmember 10" and the trough 2.4 is supported by means of rollers 23 on tWolongitudinal rails 19 parallel tothe axis of the kiln and arranged inthe hood 6. The fixed wearing sliding member 10 is applied against therotating wearing member 8 by means of weights acting in the direction ofthe arrows F, on the two lugs 22 in a manner similar to the arrangementalready described with reference to FIG. 7. The'slurry poured into thetrough 24 flows into the kiln, and, as a result of the existence of thefluid-tight rotary seal formed by the members 8 to 10, the level of thisslurry may rise upto the edge 24a of the trough without overflowing andwithout causing any leakages. It can be seen that, in this example, allthe upper section of the kiln, with the exception of the circularsegment occupied by the slurry On this flange, the wearing slidingmember 8 is and corresponding to the trough 24, is wholly available forthe passage of the gases.

In the previous examples, fluid-tightness between the fixed dam-formingmember retaining the slurry at the upper part of the kiln and therotating extremity of the latter is obtained by a rotary seal comprisingtwo wea ing sliding members heldapplied one against the other by meansof weights. It is possible to obtain the fluidtightness necessary forliquids by other means, for ex ample by means of segmet seals, and someexamples of construction comprising seals of this kind will be describedlater.

In the example shown in FIG. 9, the upper extremity of the kiln is notprovided with a collar, but is extended a little by a shell 32 havingthe same diameters as the casing 1 in order not to hinder the passage ofthe gases. In FIG. 9, the shell 32 is fixed to the casing 1 from whichit extends by means of two rings of angle-iron 33 and 34, respectivelyfixed to the casing 1 and to the shell 32 and connected to each other.The dam member serving to retain the slurry is formed by a trough 34carried by a support 35 fixed in the stationary hood 6 in such mannerthat its upper edge 24a is at the maximum retaining level provided forthe slurry in the kiln. The shell 32 penetrates in the trough throughits rear face which is extended upwards so as to form a ring 36surrounding the shell 32 with a certain clearance therebetween. Thefluid-tight segmental seal 31, for example of the type which will bedescribed with reference to FIG. 11, is mounted between the ring 86 andthe shell 32. It extends from the ring 36 in the direction of the kilnitself and may in certain cases surround a portion of the casing 1. Therings 29 which define the successive chambers of the joint are keptparallel by the U-shaped rings 30' which serve also to secure them tothe ring 36 rigidly fixed to the rear Wall of the trough.

In the device shown in longitudinal cross-section in FIG. 10, the casing1 of the kiln is extended towards the upstream side by a shell 25 whichis coaxially secured to it by means of a double flange 26 formed by apair of angle-iron rings assembled one to the other. The shell 25, thediameter of which differs only slightly from that of the casing 1 of thekiln, is provided with a wearing lining 25a secured to it in anysuitable manner. The fixed part of the device comprises a trough 24passing into the shell 25 and two rings 28 and '36 forming the laterialouter walls of the fluid-tight seal shown partly on a larger scale inFIG. 11.

The trough 24 is open at its extremity located in the shell 25, its baseand its side walls being welded to the ring 28. As has been shown in thedrawing, it may be located at a certain height above the lower generatorline of the shell 25. A metallic frame comprising in particular across-member 38 supports the trough 24 and the lower part of the ring36, and a further frame comprising the cross-member 39 carries the upperpart of the same ring 36.

As can be seen from FIG. 11, which shows only the lower half of theseal, the space included between the two rings 28 and 36 is divided intofour chambers 40 by further rings 29. The parallelism between the rings29 and the rings 28 and 36 is ensured by rings of U-section acting asspacers. The assembly of the rings 28, 29 and 36 forms a casing whichleaves radially a clearance with the shell 25. Three rows of packingrings 31 are mounted in each chamber 40; each packing ring comprises aplurality of segments extending over a portion of the periphery of theshell 25 which segments are applied against the wearing surface 25a byblade springs 41 supported at their both extremities against one segmentof a packing ring 31, with their central portions bearing against theadjacent ring 30. Suitable grooves 31a are provided for centering thesprings 41. The joints between segments of the same packing ring arearranged radially and a certain peripheral clearance is provided betweensuccessive segments in order to allow for expansion. The joints betweensuccessive packing rings are of course angularly displaced in order toincrease the path which must be followed by the slurry in order to passbetween adjacent segments.

At one or several points on the periphery of the rings 3% are providedtubes 42 which are connected to a greasing distributor 43 enabling anappropriate lubricant to be forced into the chambers 46, the lubricantbeing at a suitable pressure, so as to reduce the friction and the wearof the segments 31 against the lining 25a of the shell 25.

Half-way along its axial length, the fluid-tight seal comprises acooling chamber 44 obtained by spacing apart the rings 29' delimitingthe adjacent chamber 40, by means of an annular spacer-ring 45 formingpart of the casing of the seal and in which are screwed one or a numberof water-circulation tubes 46. In addition to its cooling action, whichreduces the risk of seizure of the fluid-tight packing rings, the wateradmitted into the chamber 44 balances the hydrostatic pressure appliedby the slurry to the joint and in consequence assists in obtainingsatisfactory fluid-tightness.

in the device of FIG. 10, fixed scrapers 47 and 48 are provided on theupstream and on the downstream side of the seal in order to detach fromthe wall of the shell 25 the half-dried slurry adhering to it.

The general arrangement of the form of embodiment shown in PEG. 12 issimilar to that shown in FIG. 10; in this case however, the normalcasing of the kiln is not extended by any shell, and the fluid-tightseal is mounted directly on the outer surface of the casing. As in oneof the previous examples, a trough 24 carried by a support 35 comprisesa rear wall which is extended upwards so as to form a ring 36surrounding with a certain clearance the metallic outer casing 1 of thekiln. In this case, the orifice pierced in the stationary hood 6 for thepassage of the upper extremity of the kiln is slightly enlarged and theseal normally provided for the passage of the kiln into the hood isincorporated in the device, as will be described later. In the figure,the fluid-tight seal which extends from the ring 36 to the ring 28 issimilar to that described with reference to FIG. 11, although it ismounted on the outside of the casing of the kiln 1. The maindifference'resides in the fact that the cooling chamber 44 is muchlarger and for that purpose, the annular spacer 45 which separates thetwo halves of the seal is replaced by a shell 37 with edges bent backoutwards at its two extremities so as to form flanges on which are fixedrespectively the two rings 29 which define the two halves of the seal.Air-tightness at the passage into the hood can easily be obtained sincethe shell 37 is station ary, the seal 5 can then be formed simply by amember fixed to this shell 37 and supported directly against the wall ofthe hood.

It will of course be understoodthat modifications may be made to'theforms of embodiment which have just been described above in particularby the substitution of equivalent technical means, without therebydeparting from the spirit or from the scope of the present invention. Inparticular, in the devices comprising a rotary seal consisting of twowearing sliding members applied one against the other, it is possible toprovide more thantwo weights for ensuring the contact, or the weightsmay be replaced by suitably arranged springs, or by other means. In thesame way, the methods of suspension and guiding of the part of thedevice which does not turn but which may in certain case be axiallydisplaceable so as to provide for expansion and longitudinal movement ofthe kiln may be other than those which have been described withreference to the drawings. In the case of the segmental seals, it isalso possible, instead of providing packing rings formed of segmentspressed by springs against a rotary member, to make use of elastic ringsoperating by their own elasticity against a wearing member which can beeasily replaced. y

it should be observed that if the total elimination of the J collar of acement kiln or of a similar member in a rotary kiln or dryer isadvantageous from the point of view of the passage of the gases and thedraught, it may not be desirable to eliminate it completely, sinceparticles of damp slurry stuck to the wall could for this reason becarried. away by the flow of gas into the stationary hood. The deviceaccording to the invention, constructed in the manner shown in FIGS. 4to 6 or 10, or in any similar manner, does not have this drawback andnevertheless enables the height of the pool of slurry in the upper partof the kiln to be substantially increased while still making available alarge outlet section for the hot gases.

What I claim is:

1. In a rotary kiln or dryer of the upwardly-inclined type, throughwhich passes a rising flow of gas intended to treat a fluid paste, pulpor slurry, means for maintaining in the lower portion of the higher endof said kiln a high level of said fluid slurry; said means comprising,in combination with the rotary shell of the kiln, a damforming memberlocated adjacent said higher end of said kiln and extending at leastover a segment of a circle forming the lower portion of thecross-section of said shell and at least up to the level to bemaintained for the fluid slurry in said kiln; a fluid-tight sealinterposed between said darn-forming member and said shell to preventthe outflow of said slurry from said kiln; means for simultaneouslyapplying said fluid-tight seal in sealing engagement with saiddam-forming member and said shell; and means for maintaining saiddam-forming member against the rotation of said shell that tends to beimparted thereto through said fluid-tight seal.

2. A rotary kiln or dryer as claimed in claim 1, in which the saiddam-forming member is constituted by a. trough partially encircling saidshell and closed at its extremities by a front and a rear wall, the edgeof said front wall rising at least up to the level to be maintained forthe fluid paste in said kiln, and said rear wall being formed with anaperture through which passes the upper end of the said shell, saidfluid-tight seal being mounted between said shell and said rear wall ofsaid trough.

, 3. A kiln or dryer as claimed in claim 1, in which said dam-formingmember is constituted by a trough entering in the upper end of the kilnand open at its extremity located in said kiln; said trough beingsecured to a drum internally disposed in said kiln and forming the innerportion of said fluid tight seal; said trough and said drum being bothsupported in a fixed position by at least one metallic frame.

4. A kiln or dryer as claimed in claim 3, in which the fluid-tight sealis of the labyrinth type and comprises a casing formed by parallelradial rings joined together in spaced relationship by spaced annuliforming with said radial rings a plurality of chambers locatingfluid-tight, packing rings resiliently urged against the rotary shell ofthe kiln for providing paste-tightness.

5. A kiln or dryer as claimed in claim 4, in which the said fluid-tightseal is divided into two portions axially separated by a chamber inwhich no fluid-tight packing rings are provided but connected with inletand outlet pipe couplings for circulating cooling water therethrough.

6. In a rotary kiln or dryer of the upwardly inclined type, throughwhich passes a rising flow of gas for drying a fluid pulp or slurry fedat the upper end of said kiln, said kiln being provided with an outercylindrical shell having an external radial flange, the provision ofmeans for maintaining in the lower port-ion of the higher end of saidkiln a high level of fluid slurry, said means comprising, a firstwearing annulus secured to the outer side of said flange directedtowards the upper end of said kiln; an external ring facing saidexternal flange adjacent the outer face thereof, said ring beingprovided laterally with a pair of lugs diametrally disposed and foldedback at right angles, said lugs carrying each a roller whose axis is atright angles with the axis of said kiln; a trough fluid tightly securedon the outer face and e,o19,sss

on the lower portion of said ring with its upper straight edge at alevel at least as high as the level to be maintained for the fluidslurry in said kiln; a second wearing annulus cooperating with the firstwearing annulus secured on the side of said ring facing said radialflange; track rails parallel to the axis of said kiln on either sidethereof for supporting said rollers, and means for permanently applyingsaid second wearing annulus against said first wearing annulus.

7. In a rotary kiin or dryer of the upwardly inclined type, throughwhich passes a rising flow of gas for drying a fiuid pulp or slurry fedat the upper end of said kiln, said kiln being provided with an outerrotary shell, the provision of means for maintaining in the lowerportion of the higher end of said kiln a high level of said fluid slurrycomprising, in combination with the rotary shell of the kiln, adam-plate located adjacent said higher end of said kiln and extendingradially beyond and in overlapping relationship at least over a segmentof a circle forming the lower portion of the cross section of said shelland at least up to the level to be maintained for the fluid slurry insaid kiln; means for urging said plate towards said edge of the inputend of said shell forming an abutment thereof; a fluid-tight sealinterposed between said plate and said shell arranged and adapted forpreventing the outflow of said slurry from said kiln; and means formaintaining said plate against the rotation of said shell that tends tobe imparted thereto through said fluid-tight seal.

8. In a rotary kiln or dryer of the upwardly inclined type, throughwhich passes a rising flow of gas for drying a fluid pulp or slurry fedat the upper end of said kiln, said kiln being provided with an outerrotary shell, the provision of means for maintaining in the lowerportion of the higher end of said kiln a high level of said fluidslurry, comprising, in combination with the rotary shell of the kiln, adam-plate located adjacent said higher end of said kiln and extendingradially beyond and in over-. lapping'relationship at least over asegment of a circle forming the lower portion of the cross section ofsaid shell and at least up to the level to be maintained for the fluidslurry in said kiln; means for urging said plate towards said edge ofthe input end of said shell forming an abutment thereof; a fluid-tightrotary seal arranged and adapted for preventing the outflow of saidslurry from said kiln comprising a pair of wearing detachable slidingmembers respectively secured to said shell and to said dam-plate on theopposing faces thereof; and means for preventing the rotation of saidplate that tends to be imparted therto through said wearing slidingmember secured to said shell.

9. In a rotary kiln or dryer of the upwardly inclined type, throughwhich passes a rising flow of gas for drying a fluid pulp or slurry fedat the upper end of said kiln, said kiln being provided with an outercylindrical shell having at least at its upper extremity a radial innerflange, the provision of means for maintaining in the higher end of saidkiln a pool of fluid slurry having at its upper extremity a depth higherthan the radial dimension of said flange, and comprising in combinationwith said flange, a wearing sliding annulus coaxial and secured to theouter side of said flange; a dam-plate located near the outer face ofsaid wearing annulus, said clam-plate having a height greater than theradial dimension of said flange, extending at least up to the level ofthe pool of slurry to be mantained in said kiln, and a transversedimension sufficient for bridging the opposite sides of said wearingannulus; means for urging said plate towards said wearing annulus; awearing sliding member secured to said plate, interposed between saidannulus and said plate and cooperating with said sliding annulus forforming a fluid-tight rotary seal preventing the outflow of said slurryfrom said pool; and means for preventing the rotation of said plate thattends to be 9 imparted thereto through the cooperating portions of saidfluid-tight rotary seal.

10. In a rotary kiln or dryer of the upwardly inclined type, throughwhich passes a rising flow of gas for drying a fluid pulp or slurry fedat the upper end of said kiln, said kiln being provided with an outercylindrical shell having at least at its upper extremity a radial innerflange, the provision of means for maintaining in the higher, end ofsaid kiln a pool of fluid slurry having at its upper extremity a depthhigher than the radial dimension of said flange, said means comprising,a wearing annulus coaxial and secured to the outer face of said flange;a dam-plate located near the outer face of said wearing annulus, saidplate having dimensions and being placed in suitable relationship foroverlapping the lower segment defined by the outer periphery of saidwearing annulus and having a horizontal edge located at alevel at leastas high as the level of the pool of slurry to be maintained in the kiln;a wearing, sliding member secured to said plate on the side thereoffacing said wearing annulus; a bar horizontally disposed opposite saidsegment and secured to said plate on the other side thereof, said barbeing pivotally secured to the lower ends of suspension rods; immovablesuspension means for pivotally securing the upper ends of saidsuspension rods; and a pair of cables connected respectively to bothends of said bar and carrying weights at their free ends, said cablespassing round a pair of pulleys located so as to maintain the strands ofthe cables secured to saidbar in a direction giving rise on both ends ofsaid bar to components of forces substantially parallel to the axis ofsaid kiln and directed towards said wearing annulus to press the wearingsliding member thereagainst.

11. In a rotary kiln or dryer of the upwardly inclined type, throughwhich passes a rising flow of gas for drying 10 a fluid pulp or slurryfed at the upper end of said kiln, said kiln being provided with anouter cylindrical shell having at least at its upper extremity a radialinner flange, the provision of means for maintaining in the higher endof said kiln a pool of fluid slurry having at its upper extremity adepth higher than the radial dimension of said flange, said meanscomprising a wearing annulus coaxial andsecured to the outer face ofsaid flange; a dam-plate located near the outer face of said wearingannulus, said plate having dimensions and being placed in suitablerelationship for overlapping the lower segment defined by the outerperiphery of 'said wearing annulus and having a horizontal edge locatedat a level at least as high as the level of the pool of slurry to bemaintained in the kiln; a wearing sliding-member secured to said plateon the side thereof facing said wearing annulus; a bar horizontallydisposed opposite said segment and secured to said plate on the otherside thereof; a pair of sliding shoes secured to both ends of saidhorizontal bar; slide tracks mounted parallel to the axis of said kilnfor guiding said sliding shoes; and a pair of cables connectedrespectively to both ends of said bar and carrying weights at their freeends, said cables passing round a pair of pulleyslocated so as tomaintain the strands of the cables secured to said bar in a directiongiving rise on both ends of said bar to components of forcessubstantially parallel to the axis of said kiln and directed towardssaid wearing annulus to press the wearing sliding member thereagainst.

References Qited in the file of this patent UNITED STATES PATENTS545,058 Cummer Aug. 27, 1895

